Seal for compressed air line drain device

Abstract

In a drain device for purging compressed air lines of water, oil, sludge, and other contaminants by the alignment of a first pair of apertures in a valving mechanism to allow the contaminants to enter a central chamber and periodically moving the central chamber to align a second pair of apertures to allow the contaminants to flow from the chamber, a pair of seals are provided for sealing each of the pairs of apertures. One seal is concentric with the one aperture in order that, with the apertures aligned, the seal will prevent leakage into or from the interior of the housing. A second seal encircles the first seal and extends radially away from the first seal in a direction coincident with the movement of the chamber portion which causes misalignment of the apertures. Accordingly, the second seal prevents escape of contaminants from the misaligned apertures while the first and second seals cooperate in the misaligned mode to prevent communication of the two apertures.

What is claimed as new is as follows: 
     
       1. In a drain device having a housing with an inlet aperture and an outlet aperture, a piston having an inlet aperture and an outlet aperture, said piston being displaceable within said housing between a first position wherein said inlet apertures are aligned, and a second position wherein said outlet apertures are aligned, the improvement comprising: first seal means concentrically positioned about said piston inlet;   second seal means of a generally oval shape and being positioned about said first seal means in an offset manner whereby a first space is created between said first seal means and said second seal means, said first space being of a greater width toward one end of said housing than toward the other end thereof;   third seal means concentrically positioned about said piston outlet;   fourth seal means of a generally oval shape and being positioned about said third seal means in an offset manner whereby a second space is created between said third seal means and said fourth seal means, said second space being of a greater width toward one end of said housing than toward the other end thereof;   said first and second seal means both serving to seal a port created when said piston and housing inlet apertures are aligned while only said third seal means serves to seal said piston and housing outlet apertures during such alignment, and further wherein said third and fourth seal means both serve to seal piston and housing outlet apertures when aligned while only said second seal means serves to seal said piston and housing inlet apertures during such alignment, and further wherein a pressure release valve is provided for actuation when said piston and housing outlet apertures are aligned and a guide ridge is provided along an interior portion of said housing, such guide ridge being positionable within a depression contained on said piston whereby rotation of said piston within said housing is prevented during a movement of the same therein.   
     
     
       2. The drain device as defined in claim 1, and further wherein said release valve is spring loaded.